The following description is provided to assist the understanding of the reader. None of the information provided or references cited is admitted to be prior art.
Tuberculosis (TB) is a serious illness that results in morbidity and mortality, if neglected. In fact, the World Health Organization has declared TB a global health emergency. TB often afflicts the poorer and malnourished segments of society. Due to the infectious nature of TB, early diagnosis is critical in controlling the disease and in reducing the trauma and cost to the patient. In the most common form of TB, pulmonary TB, active infection is diagnosed by examining the stained sputum smears of subjects by well-trained technicians. The technician looks for the presence of mycobacteria in the sputum smear; the bacilli-count is an indicator of the degree of infection.
In practice, there are two methods of staining/microscopy. The faster and more sensitive approach involves screening the sputum samples stained with auramine or rhodamine using a fluorescence microscope. However, this method is very expensive. A much cheaper method involves visually examining highly-magnified microscopic fields of Ziehl-Neelsen (ZN) stained sputum smears. Although this method is commonly practiced, it may not provide accurate results because only a few sub-regions may be examined (leading to possible omission of diagnostically important sub-regions) because it is tedious to check a large number of images. As a result, the average count of the bacilli is approximate possibly causing disease to go undiagnosed or require subsequent visits/tests. Further, the severity of the disease and its prognosis may be misestimated based on the grading of sputum smears.